24.已知 $a , b \in R$ ,若 $\left\{ a , \frac { b } { a } , 1 \right\} = \left\{ a ^ { 2 } , a + b , 0 \right\}$ ,则 $a ^ { 2019 } + b ^ { 2019 }$ 的值为()
- A. A. 1
- B. B. 0
- C. C. - 1
- D. D. $\pm 1$
Answer: C
Solution: $\because \frac { b } { a } , \therefore a \neq 0$
$\because \left\{ a , \frac { b } { a } , 1 \right\} = \left\{ a ^ { 2 } , a + b , 0 \right\}$
$\therefore \frac { b } { a } = 0$ ,即 $b = 0$ ,
$\therefore \{ a , 0,1 \} = \left\{ a ^ { 2 } , a , 0 \right\}$
$\therefore$ 当 $\left\{ \begin{array} { l } a ^ { 2 } = 1 \\ a = a \text { 时,} a = - 1 \text { 或 } a = 1 \end{array} \right.$ ,
当 $a = 1$ 时,即得集合 $\{ 1,0,1 \}$ ,不符合元素的互异性,故舍去,
当 $\left\{ \begin{array} { l } a = 1 \\ a ^ { 2 } = a \text { 时,} a = 1 \text { ,即得集合 } \{ 1,0,1 \} \text { ,不符合元素的互异性,故舍去,} \end{array} \right.$
综上,$a = - 1 , b = 0$
$\therefore a ^ { 2019 } + b ^ { 2019 } = ( - 1 ) ^ { 2019 } + 0 ^ { 2019 } = - 1$ ,